"In 2000, the psychologist Eric Turkheimer concluded that the evidence from behavioral genetic data was consistent enough to summarize in three laws. The first law holds that all human traits are heritable (i.e., genetic differences account for phenotypic differences) to some degree. This assertion may not seem all that surprising today, although the word ‘all’ is still considered provocative by some. However, twin studies have produced copious data demonstrating that almost every trait is heritable to some degree or another."